At a certain large school, in the colourful 1B class, something interesting was happening every day. Gabrysia liked to draw flowers on the blackboard, Kuba liked to build the tallest towers with blocks and Lena liked to write short stories about dragons in her notebook. Their teacher, Mrs Ola, called them "Curious Explorers", because there was nothing they didn't want to find out. One rainy morning, the children came to school a little early. The corridors were still quiet and the lights flickered slightly. Cuba walked in front of everyone, looking carefully around the walls. Suddenly he stopped and called out: - Hey! Have you seen THIS door before? In front of them was a small wooden door, hidden around the corner next to the music room. It had a shiny gold handle and there was no sign on it. Gabrysia shook her head: - I've been going here since September and I've never seen them! Lena curiously came closer and touched the handle. It was warm, as if someone had just held it. The children looked at each other with wide-open eyes. - Maybe this is the instrument room? - wondered Kuba. - Or maybe a secret room for teachers? - asked Gabrysia. Mrs Ola, who was just passing by, noticed them and smiled enigmatically: - I can see that something has caught your interest. But remember - we only open the door when we are together. The whole class gathered in front of the door. Everyone felt a thrill of excitement. Lena squeezed the door handle once more and slowly started to turn it downwards. Suddenly, a quiet sound came from the other side of the door, as if something had moved there. The children held their breath and looked at each other. What was behind the door? Did they really lead to another world? And just at that moment the door began to swing open....